Numerous designs of pallet-like support structures exist today. U.S. Pat. No. 3,490,583 to Cook, for example, illustrates in its FIG. 1 a shipping pallet (designated by the numeral "4"). Such pallet consists merely of a horizontal platform from which vertical legs depend at two opposed sides. Space underneath the horizontal platform allows entry of times of a fork-lift truck (or pallet jack) from the sides from which legs do not depend, permitting movement of the pallet when loaded with products.
Placement and use in a refrigerator or freezer of a pallet like that shown in the Cook patent is problematic for many reasons, however. Among difficulties involved in using this type of pallet in a cold environment is the low coefficient of friction of the wood or other material of which the pallet typically is formed. The Cook patent arguably attempts to address this difficulty at least partially by coating the undersides of load-containing trays, made of paperboard or wood, with a solution of synthetic latex.
Such latex coating, as described in the Cook patent, is intended primarily to prevent slippage between the trays of the load. It accordingly is not applied to the pallet itself, retaining the vulnerability of the pallet to sliding relative to the fork-life times when moved. Synthetic latex additionally is neither thermoplastic nor adequately recyclable in many circumstances. Recyclability is not expressed as an objective of the subject matter of the Cook patent, moreover, as in practice the types of pallets illustrated therein often are disposed of by chipping, shredding, burning, or dumping in landfills.
U.S. Pat. No. 5,685,233 to DeJean purports to describe a recyclable pallet assembly. Included in the assembly are support bars and stringers, all of which, according to the Abstract of the DeJean patent, "may be provided with an anti-skid surface for protecting a user walking on the pallet." The DeJean patent thereafter refers to the anti-skid material as constituting "a coating consisting of sand grit, or other particulate, intermixed with an adhesive, such as an epoxy resin," however, precluding the assembly from being recyclable and reextrudable. Again, moreover, no anti-skid material of any type is applied to the undersides of the assembly, retaining the vulnerability to sliding discussed above.
Yet another pallet is disclosed in U.S. Pat. No. 4,397,246 to Ishida, et al., which patent is incorporated herein in its entirety by this reference. Detailed in the Ishida patent is a pallet whose deck board surface is grooved so as to receive separate "slip preventing members" in the form of soft, deformable cords. Alternatively, the cords may be welded directly to the surface of the deck board. In either event, according to the Ishida patent, "each slip preventing member must project beyond the upper or lower surface of the deck board."
To provide surfaces in which the grooves may be formed, the pallet of the Ishida patent comprises a hollow rectangular molded body. Accordingly, it has an integral support base or bottom, such as is shown beneath the rectangular openings of FIGS. 1 and 3 of the Ishida patent. By contrast with the soft, deformable material from which the cords are formed, this base has the same rigidity as the remainder of the pallet. Should it crack or break, the load-distribution characteristics of the pallet may change sufficiently to preclude its further beneficial use.